Short-RInChIKey=SA-FUHFF-UHFFFADPSC-NASFABBFAH-UHFFFADPSC-NUHFF-NUHFF-NUHFF-ZZZ

In a vial, 3-azido-1-(2-chloro-4-nitrophenyl)-5-methyl-1H-pyrazole (50.0 mg, 179 μmol, 1.00 equiv) was dissolved in THF (4.00 mL) and water (4.00 mL) (1:1) and copper;sulfate (5.73 mg, 35.9 μmol, 0.200 equiv), sodium ascorbate (35.5 mg, 179 μmol, 1.00 equiv) and ethynylbenzene (23.8 mg, 25.6 μL, 233 μmol, 1.30 equiv) were added. The reaction mixture was stirred at 50 °C for 16 hours. For workup, the reaction mixture was diluted in water and extracted three times with methylene chloride. The combined organic phases were washed with water and brine, dried over Na2SO4, filtered and the solvent was removed under reduced pressure.